Serial communication interfaces between devices normally consist of a serial data line and a serial clock line. Both the serial data line and serial clock line are connected to a positive supply via a pull-up resistor and remain high when the bus is not in use. Each device using the serial communications interface is recognized by a unique address associated with the device. Each device connected to a serial bus must have an open drain or an open collector output for both the serial data line and the serial clock line. The data on the serial data line can be transferred at up to 100 kilobytes per second. The number of devices connected to the serial data line and the serial clock line are limited only by the maximum bus capacity of the lines.
Existing systems providing serial communications pass messages between devices rather than tripping individual control lines. Some digital serial data connections include a latch enabled control signal typically applied to a pin referred to as the LEN or SLEN pin. This requires most serial data interfaces to include three lines, namely, the data line, the clock line and the latch enable control signal line. If some method were available for eliminating the latch enable control signal, the number of PINs required on component packages could be greatly reduced resulting in cost savings to manufacturers.